Date: Fri, 29 Apr 2005 00:37:25 +0100 From: Pooh Bear <rabbitsfriendsandrelationsnospamail.com> Subject: Re: I think I blew my amp??!!
Malt_Hound wrote: > James Sweet wrote: > > > Actually it's more the rating of the *speaker* that's the issue. A 140W > > speaker will not handle 140W anywhere near continuously, that rating is > > music power, which assumes that the average RMS power is much lower. When an > > amplifier clips hard the output is much closer to DC at the *peak* power of > > the amplifier which is substantially higher than the RMS. > > No it's not. When an amplifier clips hard it produces a multitude of > odd harmonic frequencies of the original. It doesn't produce DC. Other > failures of amps can cause DC, but not clipping. > > > > > If you don't believe me, take a speaker rated at 140W, assuming it's 4 ohm, > > connect it to a 24V DC source (which will cause it to draw about 140W) and > > see how long it takes the voice coil to smoke. You probably won't get more > > than 10-15 seconds out of it. Tweeters usually go first, but I've seen > > *many* speakers damaged by an underpowered amp clipping, if you open one up > > the voice coil is blackened. > > > > You are comparing apples and oranges. The power rating of a speaker is > based on its impedance, not its DC resistance. They are very different > things. When using a DC coupled amplifier, it is quite common for the > amp to fail and produce a DC voltage. As you noted, this is very bad > for the speakers' voice coil, which is a pretty fine piece of wire, and > they burn out almost instantly. Indeed, the DC resistance of a speaker voice coil is typically around 60% of its' nominal impedance. More amps flow Return to Main Index
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